ui: Stores consolidation refactor (#27238)

* ui: Remove dead code from stores

- persisted() helper was exported but never used
- messageUpdateCallback / registerMessageUpdateCallback were never wired up
- conversationsStore.initialize() alias, single caller moved to init()

* ui: Merge device, theme and viewport into a single deviceStore

All three are reactive browser-environment signals, now exposed as one
class store: deviceStore.isMobile, deviceStore.isIOSDevice / isIOSSafari
/ isWKWebView / isStandalone and deviceStore.systemTheme.isDark. The
systemTheme name disambiguates the OS preference from the user theme
preference in settingsStore. Drops the unused viewport export (only
isMobile was consumed).

* ui: Merge build info into version store

One VersionStore class with build (llama.cpp build number from
build.json) and frontend (PWA version from _app/version.json),
matching the class pattern of the other stores.

* ui: Colocate context gauge popup state with its components

The gauge popup state is local UI state shared only by the
ChatFormContextGauge subtree, so it lives next to its consumers
instead of the app-scope stores barrel.

tools/ui/src/lib/components/app/chat/ChatForm/ChatFormActions/ChatFormActionAdd/ChatFormActionsAdd.svelte

@@ -2,10 +2,10 @@
 	import ChatFormActionAddButton from './ChatFormActionAddButton.svelte';
 	import ChatFormActionAddDropdown from './ChatFormActionAddDropdown.svelte';
 	import ChatFormActionAddSheet from './ChatFormActionAddSheet.svelte';
-	import { isMobile } from '$lib/stores';
+	import { deviceStore } from '$lib/stores';
 </script>
 
-{#if isMobile.current}
+{#if deviceStore.isMobile}
 	<ChatFormActionAddSheet>
 		{#snippet trigger({ disabled, onclick })}
 			<ChatFormActionAddButton {disabled} {onclick} />

tools/ui/src/lib/components/app/chat/ChatForm/ChatFormActions/ChatFormActionModels.svelte

@@ -1,6 +1,12 @@
 <script lang="ts">
 	import { ModelsSelectorDropdown, ModelsSelectorSheet } from '$lib/components/app';
-	import { chatStore, conversationsStore, isMobile, modelsStore, serverStore } from '$lib/stores';
+	import {
+		chatStore,
+		conversationsStore,
+		deviceStore,
+		modelsStore,
+		serverStore
+	} from '$lib/stores';
 
 	interface Props {
 		disabled?: boolean;
@@ -170,7 +176,7 @@
 	}
 </script>
 
-{#if isMobile.current}
+{#if deviceStore.isMobile}
 	<ModelsSelectorSheet
 		disabled={disabled || isOffline}
 		bind:this={selectorModelRef}

tools/ui/src/lib/components/app/chat/ChatForm/ChatFormContextGauge/ChatFormContextGauge.svelte

@@ -1,15 +1,14 @@
 <script lang="ts">
 	import ContextGaugeDial from './ContextGaugeDial.svelte';
-	import { useContextGauge } from '$lib/hooks/use-context-gauge.svelte';
 	import {
-		chatStore,
-		conversationsStore,
 		gaugeTriggerClick,
 		gaugeTriggerEnter,
 		gaugeTriggerKeydown,
 		gaugeTriggerLeave,
 		gaugeTriggerPointerDown
-	} from '$lib/stores';
+	} from './gauge-popup.svelte';
+	import { useContextGauge } from '$lib/hooks/use-context-gauge.svelte';
+	import { chatStore, conversationsStore } from '$lib/stores';
 	import { untrack } from 'svelte';
 
 	const gauge = useContextGauge();

tools/ui/src/lib/components/app/chat/ChatForm/ChatFormContextGauge/ContextGaugeDetails.svelte

@@ -1,9 +1,9 @@
 <script lang="ts">
 	import ContextGaugeDetailRow from './ContextGaugeDetailRow.svelte';
+	import { gaugePopup } from './gauge-popup.svelte';
 	import { ChevronDown } from '@lucide/svelte';
 	import * as Collapsible from '$lib/components/ui/collapsible';
 	import { STATS_UNITS } from '$lib/constants';
-	import { gaugePopup } from '$lib/stores/context-gauge-popup.svelte';
 
 	interface Props {
 		currentRead: number;

tools/ui/src/lib/components/app/chat/ChatForm/ChatFormContextGauge/ContextGaugePopup.svelte

@@ -2,8 +2,13 @@
 	import { colorLevelBgClass, colorLevelTextClass } from './context-gauge';
 	import ContextGaugeDetails from './ContextGaugeDetails.svelte';
 	import ContextGaugeLoadModel from './ContextGaugeLoadModel.svelte';
+	import {
+		gaugeCardEnter,
+		gaugeCardLeave,
+		gaugePopup,
+		gaugePopupClose
+	} from './gauge-popup.svelte';
 	import { useContextGauge } from '$lib/hooks/use-context-gauge.svelte';
-	import { gaugeCardEnter, gaugeCardLeave, gaugePopup, gaugePopupClose } from '$lib/stores';
 	import { formatParameters } from '$lib/utils/formatters';
 
 	const gauge = useContextGauge();

tools/ui/src/lib/components/app/chat/ChatForm/ChatFormInput/ChatFormInputBasic.svelte

@@ -1,5 +1,5 @@
 <script lang="ts">
-	import { isMobile } from '$lib/stores';
+	import { deviceStore } from '$lib/stores';
 	import { autoResizeTextarea } from '$lib/utils';
 	import { onMount } from 'svelte';
 
@@ -37,7 +37,7 @@
 	}
 
 	export function focus() {
-		if (isMobile.current) return;
+		if (deviceStore.isMobile) return;
 
 		textareaElement?.focus({ preventScroll: true });
 	}

tools/ui/src/lib/components/app/chat/ChatForm/ChatFormInput/ChatFormInputRich.svelte

@@ -1,7 +1,7 @@
 <script lang="ts">
 	import { CODE_BLOCK, CODE_TOKEN_ATTR, UI_DATA_ATTRS } from '$lib/constants';
 	import { BooleanString, ChatFormInputRichTokenKind, ColorMode } from '$lib/enums';
-	import { isMobile } from '$lib/stores';
+	import { deviceStore } from '$lib/stores';
 	import type { ChatFormInputRichToken } from '$lib/types';
 	import type { SourceHistoryEntry } from '$lib/utils';
 	import {
@@ -750,7 +750,7 @@
 		syncEmptyState();
 		document.addEventListener('selectionchange', handleSelectionChange);
 
-		if (!isMobile.current) {
+		if (!deviceStore.isMobile) {
 			rootElement?.focus({ preventScroll: true });
 		}
 	});
@@ -792,7 +792,7 @@
 	}
 
 	export function focus() {
-		if (isMobile.current) return;
+		if (deviceStore.isMobile) return;
 
 		rootElement?.focus({ preventScroll: true });
 	}

tools/ui/src/lib/components/app/chat/ChatForm/ChatFormPickers/ChatFormPickerMention.svelte

@@ -8,7 +8,7 @@
 	import { BuiltInTool, FileMentionEntryType, GlobSearchType, KeyboardKey } from '$lib/enums';
 	import { useDebouncedSearch } from '$lib/hooks/use-debounced-search.svelte';
 	import { usePickerNavigation } from '$lib/hooks/use-picker-navigation.svelte';
-	import { isMobile, settingsStore, toolsStore } from '$lib/stores';
+	import { deviceStore, settingsStore, toolsStore } from '$lib/stores';
 	import type { FileMentionEntry, GlobEntryResult } from '$lib/types';
 	import { abbreviateHome, runGlobSearchWithChildren } from '$lib/utils';
 
@@ -130,7 +130,7 @@
 		return searchError ? `Search failed - ${searchError}` : 'No matching files or folders';
 	});
 
-	const showTooltip = $derived(!isMobile.current);
+	const showTooltip = $derived(!deviceStore.isMobile);
 
 	$effect(() => {
 		if (typeof window === 'undefined') return;

tools/ui/src/lib/components/app/chat/ChatMessages/ChatMessage/ChatMessage.svelte

@@ -11,7 +11,7 @@
 	import { setChatMessageActionsContext, setChatMessageEditContext } from '$lib/contexts';
 	import { AgenticSectionType, AttachmentType, MessageRole } from '$lib/enums';
 	import { DatabaseService } from '$lib/services/database.service';
-	import { chatStore, conversationsStore, isMobile } from '$lib/stores';
+	import { chatStore, conversationsStore, deviceStore } from '$lib/stores';
 	import type {
 		ChatMessageActions,
 		ChatMessageDeletionInfo,
@@ -304,7 +304,7 @@
 
 	// After the system message flow ends, hand focus to the main chat form
 	function focusMainChatForm() {
-		if (isMobile.current) return;
+		if (deviceStore.isMobile) return;
 
 		document.querySelector<HTMLTextAreaElement>('.chat-screen-form-wrapper textarea')?.focus();
 	}

tools/ui/src/lib/components/app/chat/ChatScreen/ChatScreen.svelte

@@ -21,8 +21,7 @@
 	import {
 		chatStore,
 		conversationsStore,
-		device,
+		deviceStore,
-		isMobile,
 		serverStore,
 		settingsStore
 	} from '$lib/stores';
@@ -32,7 +31,7 @@
 	let { showCenteredEmpty = false } = $props();
 
 	let disableAutoScroll = $derived(
-		Boolean(settingsStore.config.disableAutoScroll) || isMobile.current
+		Boolean(settingsStore.config.disableAutoScroll) || deviceStore.isMobile
 	);
 	let isMobileUserScrolledUp = $state(false);
 	let mobileScrollDownHint = $state(false);
@@ -52,11 +51,11 @@
 	let hasPropsError = $derived(!!serverStore.error);
 	let isCurrentConversationLoading = $derived(chatStore.isLoading || chatStore.isStreaming());
 	let chatFormBottomPosition = $derived.by(() => {
-		if (!isMobile.current) return '1rem';
+		if (!deviceStore.isMobile) return '1rem';
 
-		if (device.isStandalone) return '1.5rem';
+		if (deviceStore.isStandalone) return '1.5rem';
 
-		if (device.isIOSSafari) return '0.25rem';
+		if (deviceStore.isIOSSafari) return '0.25rem';
 
 		return '0.5rem';
 	});
@@ -84,7 +83,7 @@
 	});
 
 	function handleMobileScroll() {
-		if (!isMobile.current) return;
+		if (!deviceStore.isMobile) return;
 
 		const container = scroll.chatScrollContainer;
 
@@ -184,7 +183,7 @@
 	}
 
 	function handleSendLikeScroll() {
-		if (!isMobile.current) {
+		if (!deviceStore.isMobile) {
 			autoScroll.enable();
 		}
 
@@ -197,7 +196,7 @@
 				'.chat-message:nth-last-child(2) .chat-message-user .chat-message-user-bubble'
 			) as HTMLElement | null;
 
-			if (isMobile.current) {
+			if (deviceStore.isMobile) {
 				// Keep the last user message bubble just above the input on mobile
 				const bubbleHeight = lastUserBubble?.scrollHeight ?? 0;
 				const baseHeight = container.scrollHeight - innerHeight;
@@ -220,7 +219,7 @@
 			}
 		}, 100);
 
-		if (isMobile.current) {
+		if (deviceStore.isMobile) {
 			autoScroll.setDisabled(disableAutoScroll);
 			mobileScrollDownHint = true;
 			mobileScrollDownHintLockedUntil = Date.now() + 500;
@@ -243,7 +242,8 @@
 
 	$effect(() => {
 		const shouldDisableAutoScroll =
-			settingsStore.config.disableAutoScroll || (isMobile.current && isCurrentConversationLoading);
+			settingsStore.config.disableAutoScroll ||
+			(deviceStore.isMobile && isCurrentConversationLoading);
 
 		autoScroll.setDisabled(shouldDisableAutoScroll);
 
@@ -266,7 +266,7 @@
 			autoScroll.enable();
 		}
 
-		if (isMobile.current && isCurrentConversationLoading) {
+		if (deviceStore.isMobile && isCurrentConversationLoading) {
 			mobileScrollDownHint = true;
 			mobileScrollDownHintLockedUntil = Date.now() + 500;
 		}
@@ -318,9 +318,9 @@
 		<div
 			class={[
 				'pointer-events-none md:sticky fixed  mt-auto transition-all duration-200',
-				device.isStandalone
+				deviceStore.isStandalone
 					? 'bottom-6 right-4 left-4'
-					: device.isIOSSafari
+					: deviceStore.isIOSSafari
 						? 'bottom-1 left-2 right-2'
 						: 'bottom-2 right-2 left-2',
 				isEmpty ? 'md:bottom-[calc(50dvh-7rem)] 2xl:bottom-[calc(50dvh-4rem)]' : 'md:bottom-4'
@@ -336,7 +336,7 @@
 			{/if}
 
 			<div class="pointer-events-none flex flex-col gap-6 items-center w-full">
-				{#if (isMobile.current ? mobileScrollDownHint || isMobileUserScrolledUp : autoScroll.userScrolledUp) && page.url.hash.includes(ROUTES.CHAT) && page.params.id}
+				{#if (deviceStore.isMobile ? mobileScrollDownHint || isMobileUserScrolledUp : autoScroll.userScrolledUp) && page.url.hash.includes(ROUTES.CHAT) && page.params.id}
 					<ChatScreenActionScrollDown
 						onclick={() => {
 							mobileScrollDownHint = false;

tools/ui/src/lib/components/app/chat/ChatScreen/ChatScreenForm.svelte

@@ -3,7 +3,7 @@
 	import { page } from '$app/state';
 	import { ChatForm } from '$lib/components/app';
 	import { useDraftMessages } from '$lib/hooks/use-draft-messages.svelte';
-	import { isMobile } from '$lib/stores';
+	import { deviceStore } from '$lib/stores';
 	import { onMount } from 'svelte';
 
 	interface Props {
@@ -120,13 +120,13 @@
 	}
 
 	onMount(() => {
-		if (!isMobile.current) {
+		if (!deviceStore.isMobile) {
 			setTimeout(focusFormUnlessCaptured, 100);
 		}
 	});
 
 	afterNavigate((navigation) => {
-		if (navigation?.from != null && !isMobile.current) {
+		if (navigation?.from != null && !deviceStore.isMobile) {
 			setTimeout(focusFormUnlessCaptured, 100);
 		}
 	});

tools/ui/src/lib/components/app/navigation/SidebarNavigation/SidebarNavigation.svelte

@@ -14,7 +14,7 @@
 	import { useKeyboardShortcuts } from '$lib/hooks/use-keyboard-shortcuts.svelte';
 	import { useMarqueeSelection } from '$lib/hooks/use-marquee-selection.svelte';
 	import { RouterService } from '$lib/services/router.service';
-	import { chatStore, conversationsStore, device, isMobile, settingsStore } from '$lib/stores';
+	import { chatStore, conversationsStore, deviceStore, settingsStore } from '$lib/stores';
 	import { buildConversationTree } from '$lib/utils';
 	import { circIn } from 'svelte/easing';
 	import { SvelteSet } from 'svelte/reactivity';
@@ -36,7 +36,7 @@
 	let logoHovered = $state(false);
 
 	const isStripExpanded = $derived(isExpandedMode || hoveredTooltip !== null);
-	const isOnMobile = $derived(isMobile.current);
+	const isOnMobile = $derived(deviceStore.isMobile);
 	const alwaysShowOnDesktop = $derived(settingsStore.config.alwaysShowSidebarOnDesktop as boolean);
 
 	$effect(() => {
@@ -65,7 +65,7 @@
 	});
 
 	$effect(() => {
-		if (isMobile.current && page.url.hash.includes(ROUTES.SEARCH)) {
+		if (deviceStore.isMobile && page.url.hash.includes(ROUTES.SEARCH)) {
 			isExpandedMode = false;
 		}
 	});
@@ -227,7 +227,7 @@
 	}
 
 	async function selectConversation(id: string) {
-		if (isMobile.current) {
+		if (deviceStore.isMobile) {
 			scheduleMobileCollapse();
 		}
 
@@ -315,9 +315,9 @@
 			'fixed md:sticky top-2 left-2 md:left-0 md:ml-2 md:mt-2 pt-2 z-10 w-[calc(100dvw-1rem)]',
 			'md:h-[calc(100dvh-1.125rem)]',
 			isExpandedMode &&
-				(device.isStandalone
+				(deviceStore.isStandalone
 					? 'h-[calc(100dvh-2rem)]'
-					: device.isIOSDevice
+					: deviceStore.isIOSDevice
 						? 'h-[calc(100dvh-0.5rem)]'
 						: 'h-[calc(100dvh-1rem)]'),
 			'rounded-3xl md:rounded-2xl',
@@ -353,7 +353,7 @@
 
 			{#if isOnMobile || (isExpandedMode && !alwaysShowOnDesktop)}
 				<div
-					class="flex items-center transition-all duration-150 ease-out {isMobile.current &&
+					class="flex items-center transition-all duration-150 ease-out {deviceStore.isMobile &&
 					!isExpandedMode
 						? 'opacity-0 h-0!'
 						: ''}"
@@ -361,7 +361,7 @@
 					out:fade={{ duration: 100 }}
 				>
 					<ActionIcon
-						icon={isMobile.current ? X : PanelLeftClose}
+						icon={deviceStore.isMobile ? X : PanelLeftClose}
 						size="lg"
 						iconSize="h-4.5 w-4.5 md:h-4 md:w-4"
 						class="backdrop-blur-none md:h-9 md:w-9 h-10 w-10 rounded-full mr-1 hover:bg-accent!"
@@ -375,9 +375,9 @@
 		</div>
 
 		<div
-			class="mt-2 flex min-h-0 flex-1 flex-col gap-4 md:gap-1 {isMobile.current
+			class="mt-2 flex min-h-0 flex-1 flex-col gap-4 md:gap-1 {deviceStore.isMobile
 				? 'transition-[opacity,height] duration-200 ease-out'
-				: ''} {isMobile.current && !isExpandedMode ? 'opacity-0 !h-0' : ''}"
+				: ''} {deviceStore.isMobile && !isExpandedMode ? 'opacity-0 !h-0' : ''}"
 			in:fade={{ duration: 200 }}
 			out:fade={{ duration: 200 }}
 		>
@@ -395,7 +395,7 @@
 					isSearchModeActive = true;
 				}}
 				onNewChat={() => {
-					if (isMobile.current) {
+					if (deviceStore.isMobile) {
 						scheduleMobileCollapse();
 					}
 				}}

tools/ui/src/lib/components/app/navigation/SidebarNavigation/SidebarNavigationActions.svelte

@@ -12,7 +12,7 @@
 		SIDEBAR_ACTIONS_ITEMS
 	} from '$lib/constants';
 	import { TooltipSide } from '$lib/enums';
-	import { isMobile } from '$lib/stores';
+	import { deviceStore } from '$lib/stores';
 	import type { Component } from 'svelte';
 	import { onMount } from 'svelte';
 	import { circIn } from 'svelte/easing';
@@ -42,7 +42,7 @@
 	let showIcons = $state(false);
 	let searchInputRef = $state<HTMLInputElement | null>(null);
 
-	const isOnMobile = $derived(isMobile.current);
+	const isOnMobile = $derived(deviceStore.isMobile);
 
 	$effect(() => {
 		if (isSearchModeActive && searchInputRef) {
@@ -107,7 +107,7 @@
 	>
 		{#each SIDEBAR_ACTIONS_ITEMS as item, i (item.tooltip)}
 			{@const isActive = isItemActive(item)}
-			{@const isSearchOnMobile = item.icon === Search && isMobile.current}
+			{@const isSearchOnMobile = item.icon === Search && deviceStore.isMobile}
 			{@const itemHref = isSearchOnMobile ? ROUTES.SEARCH : item.route}
 			{@const itemOnClick = item.route
 				? () => {
@@ -156,7 +156,7 @@
 	<div class="{className} flex-col gap-1 hidden md:flex">
 		{#each SIDEBAR_ACTIONS_ITEMS as item, i (item.tooltip)}
 			{@const isActive = isItemActive(item)}
-			{@const isSearchOnMobile = item.icon === Search && isMobile.current}
+			{@const isSearchOnMobile = item.icon === Search && deviceStore.isMobile}
 			{@const itemOnClick = item.route
 				? () => {
 						onNewChat?.();

tools/ui/src/lib/hooks/use-pwa.svelte.ts

@@ -58,7 +58,7 @@ export function usePwa() {
 		// PWA pages update via the service worker path; the storage check is the non-PWA fallback only
 		if (navigator.serviceWorker?.controller) return;
 
-		const currentVersion = versionStore.value;
+		const currentVersion = versionStore.frontend;
 
 		if (!currentVersion) return;
 

tools/ui/src/lib/stores/build-info.svelte.ts

@@ -1,45 +0,0 @@
-/**
- * buildInfoStore - llama.cpp build information
- *
- * Reads the build version from `build.json` — embedded at llama.cpp build time
- * with the llama.cpp build number (LLAMA_BUILD_NUMBER). Shown in the UI when
- * `showBuildVersion` is enabled.
- *
- * In dev mode (via `npm run dev`), falls back to `import.meta.env.DEV`'s truthy
- * value since the artifact is not produced.
- */
-
-import { browser } from '$app/environment';
-import { base } from '$app/paths';
-
-let build = $state<string>('');
-
-async function loadBuild() {
-	if (!browser) return;
-
-	if (import.meta.env.DEV) {
-		build = 'dev';
-
-		return;
-	}
-
-	try {
-		const res = await fetch(`${base}/build.json`, { cache: 'no-store' });
-
-		if (res.ok) {
-			const data = await res.json();
-
-			build = data.version ?? '';
-		}
-	} catch {
-		// build.json missing or unreachable - leave as empty string
-	}
-}
-
-loadBuild();
-
-export const buildInfoStore = {
-	get value(): string {
-		return build;
-	}
-};

tools/ui/src/lib/stores/chat.svelte.ts

@@ -109,9 +109,6 @@ class ChatStore {
 	private isEditModeActive = $state(false);
 	private addFilesHandler: ((files: File[]) => void) | null = $state(null);
 	pendingEditMessageId = $state<string | null>(null);
-	private messageUpdateCallback:
-		| ((messageId: string, updates: Partial<DatabaseMessage>) => void)
-		| null = null;
 	private _pendingDraftMessage = $state<string>('');
 	private _pendingDraftFiles = $state<ChatUploadedFile[]>([]);
 

tools/ui/src/lib/stores/conversations.svelte.ts

@@ -100,14 +100,6 @@ class ConversationsStore {
 		localStorage.setItem(REASONING_EFFORT_DEFAULT_LOCALSTORAGE_KEY, this.pendingReasoningEffort);
 	}
 
-	/**
-	 * Callback for updating message content in chatStore.
-	 * Registered by chatStore to enable cross-store updates without circular dependency.
-	 */
-	private messageUpdateCallback:
-		| ((messageId: string, updates: Partial<DatabaseMessage>) => void)
-		| null = null;
-
 	/** In-flight init run; shared by concurrent callers, reset on failure to allow retry */
 	private initPromise: Promise<void> | null = null;
 
@@ -143,23 +135,6 @@ class ConversationsStore {
 		return this.initPromise;
 	}
 
-	/**
-	 * Alias for init() for backward compatibility.
-	 */
-	async initialize(): Promise<void> {
-		return this.init();
-	}
-
-	/**
-	 * Register a callback for message updates from other stores.
-	 * Called by chatStore during initialization.
-	 */
-	registerMessageUpdateCallback(
-		callback: (messageId: string, updates: Partial<DatabaseMessage>) => void
-	): void {
-		this.messageUpdateCallback = callback;
-	}
-
 	/**
 	 *
 	 *

tools/ui/src/lib/stores/device.svelte.ts

@@ -1,5 +1,17 @@
+/**
+ * deviceStore - Browser environment signals
+ *
+ * Device capabilities, OS theme and viewport in one class store:
+ * deviceStore.isMobile, deviceStore.isIOSDevice / isIOSSafari / isWKWebView /
+ * isStandalone, deviceStore.systemTheme.isDark.
+ *
+ * UA-derived flags are static for the session; isStandalone and systemTheme
+ * track live media query changes.
+ */
+
 import { browser } from '$app/environment';
-import { MEDIA_QUERIES } from '$lib/constants';
+import { DEFAULT_MOBILE_BREAKPOINT, MEDIA_QUERIES } from '$lib/constants';
+import { MediaQuery } from 'svelte/reactivity';
 
 /**
  * iOS UA token detection.
@@ -17,53 +29,60 @@ const UA_PATTERNS = {
 	WEBVIEW_IOS: /CriOS|FxiOS|EdgiOS|GSA/
 } as const;
 
-interface DeviceContext {
+class DeviceStore {
 	/** Any iOS/iPadOS device, regardless of which app or browser embeds the page. */
-	isIOSDevice: boolean;
+	readonly isIOSDevice: boolean = false;
 	/** The Safari browser app on iOS, excluding other iOS browsers and WKWebViews. */
-	isIOSSafari: boolean;
+	readonly isIOSSafari: boolean = false;
 	/** Any WKWebView context on iOS: in-app browsers, embedded web views, and the
 	 *  third-party iOS browsers (all of which share the WKWebView engine). */
-	isWKWebView: boolean;
+	readonly isWKWebView: boolean = false;
 	/** PWA standalone mode: the page was launched from the home screen icon. */
-	isStandalone: boolean;
+	isStandalone = $state(false);
+	/** OS color scheme preference; the user override lives in settingsStore. */
+	readonly systemTheme = $state({ isDark: false });
+
+	private mobile = new MediaQuery(`max-width: ${DEFAULT_MOBILE_BREAKPOINT - 1}px`);
+
+	get isMobile(): boolean {
+		return this.mobile.current;
 	}
 
-const SERVER_DEFAULT: DeviceContext = {
+	constructor() {
-	isIOSDevice: false,
+		if (!browser) return;
-	isIOSSafari: false,
-	isStandalone: false,
-	isWKWebView: false
-};
-
-function detect(): DeviceContext {
-	if (!browser) return SERVER_DEFAULT;
 
 		const ua = navigator.userAgent;
 		const isTouch = navigator.maxTouchPoints > 0;
-	const isIOSDevice = UA_PATTERNS.IOS_PHONE.test(ua) || (UA_PATTERNS.MACINTOSH.test(ua) && isTouch);
+
+		this.isIOSDevice =
+			UA_PATTERNS.IOS_PHONE.test(ua) || (UA_PATTERNS.MACINTOSH.test(ua) && isTouch);
 		// Safari keeps 'Safari/' in the UA; non-Safari iOS browsers emit their own
 		// token instead. WKWebView typically omits 'Safari/' entirely.
 		const hasSafariToken = UA_PATTERNS.SAFARI.test(ua) && !UA_PATTERNS.WEBVIEW_IOS.test(ua);
-	const isIOSSafari = isIOSDevice && hasSafariToken;
+
-	const isWKWebView = isIOSDevice && !hasSafariToken;
+		this.isIOSSafari = this.isIOSDevice && hasSafariToken;
+		this.isWKWebView = this.isIOSDevice && !hasSafariToken;
 		// navigator.standalone is the legacy iOS-only flag (deprecated but still
 		// present); display-mode: standalone is the modern standard (Safari 16.4+).
-	const isStandalone =
+		this.isStandalone =
 			window.matchMedia(MEDIA_QUERIES.DISPLAY_MODE_STANDALONE).matches ||
 			(navigator as Navigator & { standalone?: boolean }).standalone === true;
+		this.systemTheme.isDark = window.matchMedia(MEDIA_QUERIES.PREFERS_DARK).matches;
 
-	return { isIOSDevice, isIOSSafari, isStandalone, isWKWebView };
+		// isStandalone and systemTheme can change at runtime (e.g. user installs the
-}
+		// PWA while the tab is open); the UA-derived flags are static for the session
+		const standaloneMql = window.matchMedia(MEDIA_QUERIES.DISPLAY_MODE_STANDALONE);
 
-export const device = $state<DeviceContext>(detect());
+		standaloneMql.addEventListener('change', (e) => {
+			this.isStandalone = e.matches;
+		});
 
-if (browser) {
+		const darkMql = window.matchMedia(MEDIA_QUERIES.PREFERS_DARK);
-	// isStandalone can change at runtime (e.g. user installs the PWA while the
-	// tab is open); the UA-derived flags are static for the session.
-	const mql = window.matchMedia(MEDIA_QUERIES.DISPLAY_MODE_STANDALONE);
 
-	mql.addEventListener('change', (e) => {
+		darkMql.addEventListener('change', (e) => {
-		device.isStandalone = e.matches;
+			this.systemTheme.isDark = e.matches;
 		});
 	}
+}
+
+export const deviceStore = new DeviceStore();

tools/ui/src/lib/stores/index.ts

@@ -53,26 +53,6 @@ export { permissionsStore } from './permissions.svelte';
 export { toolsStore } from './tools.svelte';
 
 // ENVIRONMENT / META
-export { buildInfoStore } from './build-info.svelte';
-
 export { versionStore } from './version.svelte';
 
-export { device } from './device.svelte';
+export { deviceStore } from './device.svelte';
-
-export { viewport, isMobile } from './viewport.svelte';
-
-export { theme } from './theme.svelte';
-
-export {
-	gaugePopup,
-	gaugePopupClose,
-	gaugeTriggerPointerDown,
-	gaugeTriggerClick,
-	gaugeTriggerKeydown,
-	gaugeTriggerEnter,
-	gaugeTriggerLeave,
-	gaugeCardEnter,
-	gaugeCardLeave
-} from './context-gauge-popup.svelte';
-
-export { persisted } from './persisted.svelte';

tools/ui/src/lib/stores/persisted.svelte.ts

@@ -1,51 +0,0 @@
-import { browser } from '$app/environment';
-
-type PersistedValue<T> = {
-	get value(): T;
-	set value(newValue: T);
-};
-
-export function persisted<T>(key: string, initialValue: T): PersistedValue<T> {
-	let value = initialValue;
-
-	if (browser) {
-		try {
-			const stored = localStorage.getItem(key);
-
-			if (stored !== null) {
-				value = JSON.parse(stored) as T;
-			}
-		} catch (error) {
-			console.warn(`Failed to load ${key}:`, error);
-		}
-	}
-
-	const persist = (next: T) => {
-		if (!browser) {
-			return;
-		}
-
-		try {
-			if (next === null || next === undefined) {
-				localStorage.removeItem(key);
-
-				return;
-			}
-
-			localStorage.setItem(key, JSON.stringify(next));
-		} catch (error) {
-			console.warn(`Failed to persist ${key}:`, error);
-		}
-	};
-
-	return {
-		get value() {
-			return value;
-		},
-
-		set value(newValue: T) {
-			value = newValue;
-			persist(newValue);
-		}
-	};
-}

tools/ui/src/lib/stores/settings.svelte.ts

@@ -40,9 +40,9 @@ import {
 } from '$lib/constants';
 import { ColorMode } from '$lib/enums';
 import { ParameterSyncService } from '$lib/services/parameter-sync.service';
+import { deviceStore } from '$lib/stores/device.svelte';
 // direct imports between stores, not via the barrel, to avoid circular deps
 import { serverStore } from '$lib/stores/server.svelte';
-import { isMobile } from '$lib/stores/viewport.svelte';
 import type { SettingsExportType } from '$lib/types';
 import {
 	configToParameterRecord,
@@ -138,7 +138,7 @@ class SettingsStore {
 
 			// Default sendOnEnter to false on mobile when the user has no saved preference
 			if (!(SETTINGS_KEYS.SEND_ON_ENTER in savedVal)) {
-				if (isMobile.current) {
+				if (deviceStore.isMobile) {
 					this.config[SETTINGS_KEYS.SEND_ON_ENTER] = false;
 				}
 			}

tools/ui/src/lib/stores/theme.svelte.ts

@@ -1,14 +0,0 @@
-import { browser } from '$app/environment';
-import { MEDIA_QUERIES } from '$lib/constants';
-
-export const theme = $state({
-	isSystemDark: browser && window.matchMedia(MEDIA_QUERIES.PREFERS_DARK).matches
-});
-
-if (browser) {
-	const mql = window.matchMedia(MEDIA_QUERIES.PREFERS_DARK);
-
-	mql.addEventListener('change', (e) => {
-		theme.isSystemDark = e.matches;
-	});
-}

tools/ui/src/lib/stores/version.svelte.ts

@@ -1,44 +1,61 @@
 /**
- * versionStore - Frontend build version
+ * versionStore - Build version information
  *
- * Reads from SvelteKit's `_app/version.json` — generated by the @vite-pwa/sveltekit
+ * - `build`: llama.cpp build number from `build.json`, embedded at llama.cpp
- * plugin. The version string changes on every build, so comparing it against
+ *   build time (LLAMA_BUILD_NUMBER). Shown in the UI when `showBuildVersion`
- * localStorage reliably detects server upgrades.
+ *   is enabled.
+ * - `frontend`: frontend build version from SvelteKit's `_app/version.json`,
+ *   generated by the @vite-pwa/sveltekit plugin. Changes on every build, so
+ *   comparing it against localStorage reliably detects server upgrades.
  *
- * In dev mode, falls back to `'dev'`.
+ * In dev mode both fall back to `'dev'`.
  */
 
 import { browser } from '$app/environment';
 import { base } from '$app/paths';
 
-let version = $state<string>('');
+class VersionStore {
+	build = $state<string>('');
+	frontend = $state<string>('');
 
-async function loadVersion() {
+	constructor() {
 		if (!browser) return;
 
 		if (import.meta.env.DEV) {
-		version = 'dev';
+			this.build = 'dev';
+			this.frontend = 'dev';
 
 			return;
 		}
 
+		void this.load();
+	}
+
+	private async load(): Promise<void> {
+		try {
+			const res = await fetch(`${base}/build.json`, { cache: 'no-store' });
+
+			if (res.ok) {
+				const data = await res.json();
+
+				this.build = data.version ?? '';
+			}
+		} catch {
+			// build.json missing or unreachable - leave as empty string
+		}
+
 		try {
 			const res = await fetch(`${base}/_app/version.json`, { cache: 'no-store' });
 
 			if (res.ok) {
 				const data = await res.json();
 
-			version = data.version ?? '';
+				this.frontend = data.version ?? '';
 			}
 		} catch {
-		// _app/version.json missing or unreachable - leave as empty string
+			// version.json missing or unreachable - leave as empty string
+		}
 	}
 }
 
-loadVersion();
+export const versionStore = new VersionStore();
-
-export const versionStore = {
-	get value(): string {
-		return version;
-	}
-};

tools/ui/src/lib/stores/viewport.svelte.ts

@@ -1,9 +0,0 @@
-import { browser } from '$app/environment';
-import { DEFAULT_MOBILE_BREAKPOINT } from '$lib/constants';
-import { MediaQuery } from 'svelte/reactivity';
-
-export const viewport = $state({
-	width: browser ? window.innerWidth : 0
-});
-
-export const isMobile = new MediaQuery(`max-width: ${DEFAULT_MOBILE_BREAKPOINT - 1}px`);

tools/ui/src/routes/(chat)/+page.svelte

@@ -77,7 +77,7 @@
 
 	onMount(async () => {
 		if (!conversationsStore.isInitialized) {
-			await conversationsStore.initialize();
+			await conversationsStore.init();
 		}
 
 		conversationsStore.clearActiveConversation();

tools/ui/src/routes/+layout.svelte

@@ -19,15 +19,14 @@
 	import { usePwa } from '$lib/hooks/use-pwa.svelte';
 	import { RouterService } from '$lib/services/router.service';
 	import {
-		buildInfoStore,
 		chatStore,
 		conversationsStore,
-		isMobile,
+		deviceStore,
 		mcpStore,
 		modelsStore,
 		serverStore,
 		settingsStore,
-		theme
+		versionStore
 	} from '$lib/stores';
 	import { ModeWatcher } from 'mode-watcher';
 	import { untrack } from 'svelte';
@@ -55,7 +54,7 @@
 	const { needRefresh, updateServiceWorker } = pwa;
 
 	function updateFavicon() {
-		const dark = theme.isSystemDark;
+		const dark = deviceStore.systemTheme.isDark;
 
 		let icoLink = document.querySelector(FAVICON_SELECTORS.ICO_48X48) as HTMLLinkElement | null;
 
@@ -153,7 +152,7 @@
 	}
 
 	$effect(() => {
-		void theme.isSystemDark;
+		void deviceStore.systemTheme.isDark;
 
 		updateFavicon();
 	});
@@ -274,7 +273,7 @@
 	<div class="flex flex-col md:flex-row">
 		<SidebarNavigation
 			onSearchClick={() => {
-				if (isMobile.current) {
+				if (deviceStore.isMobile) {
 					goto(ROUTES.SEARCH);
 				} else if (chatSidebar?.activateSearchMode) {
 					chatSidebar.activateSearchMode();
@@ -294,8 +293,8 @@
 
 <!-- PWA update prompt + version -->
 <div class="fixed right-4 bottom-4 z-9999 flex flex-col items-end gap-1">
-	{#if showBuildVersion && buildInfoStore.value}
+	{#if showBuildVersion && versionStore.build}
-		<span class="text-[10px] tabular-nums text-muted-foreground">{buildInfoStore.value}</span>
+		<span class="text-[10px] tabular-nums text-muted-foreground">{versionStore.build}</span>
 	{/if}
 
 	<PwaRefreshAlert

tools/ui/src/routes/search/+page.svelte

@@ -5,7 +5,7 @@
 	import { SearchInput, SidebarNavigationSearchResults } from '$lib/components/app';
 	import { ROUTES } from '$lib/constants';
 	import { RouterService } from '$lib/services/router.service';
-	import { chatStore, conversationsStore, isMobile } from '$lib/stores';
+	import { chatStore, conversationsStore, deviceStore } from '$lib/stores';
 
 	let searchQuery = $state('');
 	let searchInputRef = $state<HTMLInputElement | null>(null);
@@ -23,7 +23,7 @@
 	// Search page is intended for mobile; on desktop the sidebar already exposes
 	// in-place search, so bounce back to a chat.
 	$effect(() => {
-		if (browser && !isMobile.current) {
+		if (browser && !deviceStore.isMobile) {
 			goto(ROUTES.NEW_CHAT, { replaceState: true });
 		}
 	});